3. The River section for the Soo Area Office (U.S. Army Corps of Engineers) is responsible for 550 miles of coastline, and 10 federal harbors.
4. The hard sandstone that creates the rapids and makes the river impassible is part of the Jacobsville formation and the same stone that makes Pictured Rocks. Here at the Soo the stone extends up to 1,000 feet below the surface. The pink color comes from iron trapped in the rock.